docs: def get_reflectance_lut(filename):
      """Read the LUT with reflectances as a function of wavelength, satellite
      zenith secant, azimuth difference angle, and sun zenith secant
  
      """
  
      h5f = h5py.File(filename, 'r')
  
      tab = h5f['reflectance']
      wvl = h5f['wavelengths']
      azidiff = h5f['azimuth_difference']
      satellite_zenith_secant = h5f['satellite_zenith_secant']
      sun_zenith_secant = h5f['sun_zenith_secant']
  
      if HAVE_DASK:
          tab = from_array(tab, chunks=(10, 10, 10, 10))
          wvl = wvl[:]  # no benefit to dask-ifying this
          azidiff = from_array(azidiff, chunks=(1000,))
          satellite_zenith_secant = from_array(satellite_zenith_secant,
                                               chunks=(1000,))
          sun_zenith_secant = from_array(sun_zenith_secant,
                                         chunks=(1000,))
      else:
          # load all of the data we are going to use in to memory
          tab = tab[:]
          wvl = wvl[:]
          azidiff = azidiff[:]
          satellite_zenith_secant = satellite_zenith_secant[:]
          sun_zenith_secant = sun_zenith_secant[:]
          h5f.close()
  
      return tab, wvl, azidiff, satellite_zenith_secant, sun_zenith_secant